Semiconductor input protection circuit

Abstract

Abstract PURPOSE:To ensure a sufficient connector contact current even under bad environment specific to a vehicle and to eliminate noise without losing surge immunity by providing a switch circuit in parallel with a pullup resistor and turning on the said switch circuit while the sampling circuit applies no sampling. CONSTITUTION:A semiconductor input protection circuit 21 consists of a high frequency noise rejection capacitor 23, diodes 24, 25 for voltage clamp for overvoltage input protection, a pullup resistor 26, a buffer circuit 30 for waveform shaping, a sampling circuit 31, an oscillator 32, a switch circuit 33 and an inverter circuit 34. The switch circuit 33 is turned off while the sampling circuit 31 applies sampling and the switch circuit 33 is turned off while no sampling is applied to short-circuit the pullup resistor 26 thereby obtaining a large current flowing to the protection resistor 22. Thus, a connector contact current ensuring the oxide film of the contact of a wire connector to be broken surely flows to the contact.

Inventors

• 👤 Takashi Kimura
• 👤 隆志 木村
• 👤 Noriyuki Abe
• 👤 憲幸 阿部
• 👤 Norio Fujiki
• 👤 憲夫 藤木

Bibliographic Details